The present invention relates to an apparatus for feeding a sheet-like members (which will be referred hereinafter to as sheets) in image recording system such as a printer, a copying machine and a facsimile equipment.
A conventional sheet feeding apparatus will be described hereinbelow with reference to FIGS. 11 to 13. In FIG. 11, the sheet feeding apparatus comprises a sheet feeding roller 27 having a substantially cylindrical configuration for successively feeding sheets 33 placed one upon another, a portion of which is cut off in the directions of the axis of a roller rotating shaft 3. This sheet feeding roller 27 is supported by the roller rotating shaft 3 and a one-revolution clutch (not shown) is incorporated into the roller rotating shaft 3. Also included in the sheet feeding apparatus is a separation pad 8 provided within the sheet feeding apparatus so as to be supported to be movable in directions indicated by an arrow F. This separation pad 8 is biased toward the sheet feeding roller 27 side by means of a spring 9. Further, included in the apparatus is a separation idler roller 28 rotatably supported by the roller rotating shaft 3 and having a radius slightly smaller than the radius of the sheet feeding roller 27. When the cut-off portion of the sheet feeding roller 27 moves in accordance with its rotation to face the separation pad 8, the separation idler roller 28 comes into contact with the separation pad 8. Designated at numeral 6 is a sheet storing (keeping) device end portions of which are slidably (movably) supported within the apparatus. This sheet storing device 6 is biased by means of a spring 7 toward the sheet feeding roller 27 side. Further, numeral 29 represents an upper guide for guiding the sheets 33 in conveying, numeral 30 represents an lower guide for the sheet 33 in conveying, and numerals 31, 32 are conveying rollers for conveying sheets 33, separated one by one through the sheet feeding roller 27 and fed therefrom, toward an image formation apparatus (not shown) which is disposed at a downstream portion in the conveying direction. Here, when the frictional forces between the sheet feeding roller 27 and the sheet 33, between the separation pad 8 and the sheet 33 and between the sheets 33 are respectively taken to be Q, R and S, the relation between the frictional forces is Q&gt;R&gt;S.
A description will be made hereinbelow in terms of the operation of the conventional sheet feeding apparatus thus arranged. In the case of no feeding and conveying of the sheets 33, as illustrated in FIG. 11, the relation in position between the sheet feeding roller 27, the separation pad 8, the separation idler roller and the sheets 33 is that the sheet feeding roller 27 stops with the cut-off portion thereof being positioned at the lower side and the separation pad 8 is brought into contact with the separation idler roller 28 by means of the biasing force of the spring 9. This separation idler roller 28 also comes into contact with the sheets 33 held within the sheet storing device 6 because the sheet storing device 6 is biased upwardly by the spring 7. For starting the sheet feeding operation, the sheet feeding roller 27 is rotated in a direction indicated by an arrow G so as to come into contact with the sheet 33. When the sheet feeding roller 27 further rotates, as illustrated in FIG. 12, the sheet feeding roller 27 downwardly presses the separation pad 8 so that the sheets 33 are supplied toward between the sheet feeding roller 27 and the separation pad 8. At this time, only the uppermost sheet 33a of the sheets 33 is fed due to the difference between the frictional forces of the separation pad 8 and sheet feeding roller 27 with respect to the sheet 33.
When supplying the sheet 33a, due to the one-revolution clutch the sheet feeding roller 27 operates by one revolution to convey the sheet 33a by a predetermined distance and then stops to take a state as illustrated in FIG. 13. The conveying distance corresponding to the one revolution of the sheet feeding roller 27 is set to be longer than the distance between the conveying rollers 31, 32 and the sheet feeding roller 27. After being conveyed by the sheet feeding roller 27, the sheet 33a is supplied into an image formation apparatus (not shown). At this time, although the sheet 33a is brought into contact with the separation idler roller 28 by means of the separation pad 8, the separation idler roller 28 is rotatably supported by the roller rotating shaft 3 so as to be rotated in accordance with the movement of the sheet 33a, thus not affecting the conveying of the sheet 33a. After the completion of the conveying of the sheet 33a, the sheet feeding roller 27 again starts to rotate to perform the similar sheet feeding and separating operation.
As obvious from the above description, such a conventional sheet feeding apparatus requires two conveying means, i.e., the sheet feeding roller 27 and the conveying rollers 31, 32, for the separation and feeding of the sheet 33a. This causes increase in cost and size of the apparatus.